Why does my displacement look jagged - Cycles?
Your displacement map does not have enough information to create a smooth result. You should be using images in 16 bit per channel (or higher) and not crappy jpgs (8bit per channel compressed).

On top of that you should not use sRGB for either map, but Non-color. sRGB will distort the map information.

Additional info on the following links:

Which color space should I use for 16-bit maps?

Would a 16-bit image for a bump map have any advantage?

How to get rid of the odd lines shown in the image?